Persistent pain is the number one reason that patients access the healthcare system according to the National institutes of Health. Pain seriously affects patients' quality of life and is associated with secondary morbidities such as depression, anxiety, and sleep disturbance. Medications are often the first-line treatment for pain relief, but they are not without serious side effects. Particularly for rural citizens and socioeconomic disadvantaged individuals very few non-pharmacotherapy regimes exist to help manage pain. Ultrasound has been used safely and effectively for years to provide pain relief. Additionally, the mechanical and thermal mechanisms of action in ultrasound have been shown to facilitate wound and bone fracture healing, to promote the penetration of topical ointments into the skin and found to enhance a variety healthcare applications. Despite the potential of ultrasound therapy, the size, price, and mode of delivery has prohibited its broad translation. We have developed a new ultrasound device that provides a unique platform solution for ultrasound in frontline medicine in disparate and socioeconomic disadvantaged communities. The system relies on aggressive miniaturization and integration of the ultrasound transducer, electronics, and power supply to produce an iPod- sized low-intensity ultrasound system that can deliver portable, convenient, and effective therapy for long durations. For this project, the iPod-sized ultrasound devices will be refined and clinically evaluated on subjects with osteoarthritis of the knee. Subjects will be asked to wear the device for 6 hours a day over the duration of the study, and will be monitored for reductions in pain, increased mobility and their use of pharmaceuticals for pain control. Successful completion of the study will increase scientific understanding of the efficacy of low- intensity continuous ultrasound treatment on musculoskeletal pain and mobility from OA, and provide the first non-invasive, portable, transformative solution to pain control.